This request is for funds to purchase a single photon Zeiss 510 confocal microscope. This instrument will be housed within the Center for Biologic Imaging (CBI) at the University of Pittsburgh School of Medicine. The mandate of this core facility is to provide access to a full range of light and electron optical, image analysis, and morphometric methods to all research groups within the University of Pittsburgh School of Medicine. Confocal microscopy is an essential service provided by the center, the current core use confocal microscopes within the facility are a 4 year old Leica TCS-NT and a 10 year old Molecular Dynamics 2001. The reasons for this application are to: 1: Provide critically needed instrument time; 2: Replace the Molecular Dynamics instrument which is no longer servicable as a core microscope; 3: Provide access to requested confocal technologies, specifically selected area FRAP and beam blanking not available with the current microscopes in the center Since the CBI commenced operations 9 years ago, it has become an integral part of the medical research community currently participating in research projects with more than 50 PHS funded groups within the medical area, as well as in PHS supported projects with investigators at neighboring institutions As the PHS funded user base continues to expand, a lack of available confocal tune has become a major limiting factor in the utility of the center, this leads to considerable frustration amongst users. The acquisition of the requested instrument will allow individual users more ready access to confocal microscopy such that the current user bottle neck for the current instrument will be resolved.